1. Field of the Invention
The present invention relates to a magnetic head for perpendicular magnetic recording that is used for writing data on a recording medium by means of a perpendicular magnetic recording system, and more specifically, to a magnetic head for perpendicular magnetic recording that includes a heater for allowing the end face of the main pole located in the medium facing surface to protrude.
2. Description of the Related Art
The recording systems of magnetic read/write apparatuses include a longitudinal magnetic recording system in which signals are magnetized in a direction along the plane of a recording medium (the longitudinal direction) and a perpendicular magnetic recording system in which signals are magnetized in a direction perpendicular to the plane of a recording medium. It is known that the perpendicular magnetic recording system is harder to be affected by thermal fluctuation of the recording medium and capable of providing higher linear recording density, compared with the longitudinal magnetic recording system.
Magnetic heads for perpendicular magnetic recording typically have, like those for longitudinal magnetic recording, a structure in which a read head unit having a magnetoresistive element (hereinafter, also referred to as MR element) for reading and a write head unit having an induction-type electromagnetic transducer for writing are stacked on a substrate. The write head unit includes a coil and a main pole. The main pole has an end face located in a medium facing surface facing a recording medium. The coil produces a magnetic field corresponding to data to be written on the recording medium. The main pole allows a magnetic flux corresponding to the magnetic field produced by the coil to pass, and produces a write magnetic field from its end face.
A magnetic head for use in a magnetic disk drive such as a hard disk drive is typically in the form of a slider. The slider has the medium facing surface. The medium facing surface has an air inflow end (a leading end) and an air outflow end (a trailing end). The slider is designed to slightly fly over the surface of a recording medium by means of an airflow that comes from the leading end into the space between the medium facing surface and the recording medium.
It is demanded of magnetic disk drives that the distance from the end face of the main pole located in the medium facing surface to the surface of the recording medium be reduced in order to provide higher recording densities while preventing the writing capability of the write head unit from being reduced with higher density recording. To meet this, there has been proposed a technology of heating the main pole with a heater to allow the end face of the main pole to protrude to thereby reduce the distance from the end face of the main pole to the surface of the recording medium, as disclosed in U.S. Patent Application Publication Nos. 2009/0251828 A1 and 2012/0218662 A1, for example. U.S. Patent Application Publication Nos. 2009/0251828 A1 and 2012/0218662 A1 each disclose a magnetic head with a heater provided within an insulating layer near the main pole.
JP 2008-77751A discloses a magnetic head including a heater and a thermal conductive layer disposed near the heater.
In a conventional magnetic head including a heater for heating the main pole, components of the write head unit other than the main pole are also heated by the heater. A typical component of the write head unit other than the main pole is a write shield disclosed in U.S. Patent Application Publication No. 2012/0218662 A1. The write shield has an end face located near the end face of the main pole in the medium facing surface.
For the conventional magnetic head including the heater, since the components of the write head unit other than the main pole are also heated by the heater as mentioned above, it is difficult to allow the end face of the main pole to greatly protrude relative to its neighboring surroundings located in the medium facing surface. The conventional magnetic head thus has a disadvantage that the distance from the end face of the main pole to the surface of the recording medium cannot be sufficiently reduced and therefore it is not possible to achieve sufficiently high recording density. Further, for the conventional magnetic head, the end face of the main pole does not always protrude by the greatest amount when compared with the other parts of the end face of the write head unit located in the medium facing surface. If any part of the end face of the write head unit other than the end face of the main pole protrudes by the greatest amount, it becomes difficult to recognize and control the distance from the end face of the main pole to the surface of the recording medium.